共查询到19条相似文献,搜索用时 218 毫秒
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采用紫铜电极、Cu W70在变化的峰值电流(I)、脉冲宽度(ton)电参数下加工8418钢,研究电极材料及电参数对电火花加工表面质量的影响。测得了工件表面粗糙度、微观硬度、白层厚度、微裂纹,结果表明:采用紫铜电极加工时工件表面粗糙度(Ra)及白层厚度(WT)均比采用Cu W70时略大,但在精加工放电参数下,电极材料对表面粗糙度的影响区别并不明显。工件表面粗糙度与白层厚度随着峰值电流和脉宽的增大而增大,且峰值电流对白层厚度的增加起主要作用。显微硬度随着与工件表面距离的增大而急剧减小。在低放电能量时,两种电极加工的8418钢表面基本上没有微裂纹,质量较好;在中高放电能量时,紫铜电极加工的工件表面微裂纹的数量比Cu W70电极的要多,但裂纹宽度差别不大。 相似文献
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提出一种混粉准干式电火花加工技术,其加工介质是气液固三相流混合物。试验结果表明,材料去除率与表面粗糙度随脉冲宽度、峰值电流及分层厚度的增大而增大,脉冲间隙作用则相反,提高空气压力既有助于提高材料去除率又可降低表面粗糙度,电极损耗随脉冲宽度增大而减小,当脉冲宽度较大时电极损耗接近于零,随峰值电流增大而增加。由于液滴、粉末的介入,气体介质的绝缘强度降低,放电间隙会增加,有利于电蚀产物的排除,可减少短路、电弧放电的发生率,加工稳定性得到提高,从而材料去除率得到提高;由于粉末会产生放电分散效果,电蚀凹坑深度减小,工件表面粗糙度降低。 相似文献
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为改善高电阻率硅的电火花线切割可加工性,提出了一种在半导体电镀金属薄膜表面放电的方法(简称进电端放电法)。首先在硅(电阻率为2.1Ω·cm)表面电镀一层铜膜,然后利用铜刷作电极,在铜膜表面进行放电,利用放电形成的高温在硅表面形成重掺杂层,以降低接触势垒。分析了表面重掺杂层的形成机理,制备了硅试件并得到了伏安曲线,结果表明,试件的进电端接触电阻明显减小。最后采用进电端放电法对电阻率为2.1Ω·cm、直径为100mm的硅锭进行电火花线切割试验,加工效率可由12mm2/min提高至30mm2/min。 相似文献
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采用紫铜工具电极,在峰值电流为4-24A、脉冲宽度为25-200μs、加工电压为80-200V的电参数范围内,综合应用因子试验和正交试验方法,对难加工材料4Cr5MoVSi进行了电火花加工试验。在进行电加工基础特征规律分析的基础上,考查了电参数对加工速度、双边侧面放电间隙、电极损耗的影响,并对电火花加工机理进行了分析。研究结果表明:采用紫铜电极电火花加工4Cr5MoVSi,在本试验范围内,峰值电流Ip与脉冲宽度ti、加工电压U、脉冲间隔t0存在一定的交互作用;与其它三个因素相比,峰值电流对加工速度、电极损耗、双边侧面放电间隙的影响更显著;随脉冲宽度和加工电压的增大,电极损耗逐渐减小。 相似文献
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针对铝合金材料在电火花线切割加工过程中,出现进电不稳、电极丝与导电块之间产生异常放电"火花"及导电块在很短的时间内被切割出沟槽现象,设计制造了一种铝合金线切割加工进电装置。该进电装置设计合理,结构简单,能够有效地提高硬质合金导电块的使用寿命及改善进电不稳定的问题,从而降低了生产成本,其经济效益十分显著。 相似文献
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Pil Joo Cho Bo Hyun Kim Deok Ki Choi Chong Nam Chu 《Journal of Mechanical Science and Technology》2008,22(2):300-307
Micro electrical discharge machining (MEDM) is a promising technology for fabricating micro-parts on a variety of materials.
An RC circuit is suitable for MEDM because it produces low pulse width and relatively high peak current. However, it is not
well understood how circuit elements affect machining characteristics of MEDM. In this paper, the effects of circuit elements
on MEDM of micro-holes and the relation between characteristic variables of process and machining characteristics was investigated.
Since the discharge inductance causes an increase in electrode wear and machining time, it should be minimized in MEDM. From
this study, it should be less than a few μH. The machining time also increases with increasing the charging resistance. If
the charging resistance is less than a few hundreds Ω, however, continuous arc discharge occurs and the machining speed is
markedly reduced. 相似文献
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This article presents a new method for discrimination of various types of pulses generated during an electrical discharge machining process in presence of a rotating electrode. Existing pulse discrimination methods do not perform efficiently in an electrical discharge machine with rotating electrode, as arcs rarely occur during the machining process. Our method involves simultaneous comparison of the gap voltage and current signals with various thresholds. The main advantage of our proposed method is its efficient computation and significantly better accuracy in discriminating between various pulse classes for electrical discharge machining devices with rotating electrode. Experimental studies demonstrate a superior performance of our method in distinguishing normal pulses from harmful arcs, open circuit and short circuit pulses, compared with the state-of-art methods. 相似文献
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针对钢板桩遇密实土层难以沉桩的问题,设计了一种新型液力自旋式喷嘴结构。基于流体力学理论,利用Fluent软件,通过改变斜射流口的偏心距、斜射流口与水平面的夹角等结构参数,得到了该喷嘴内腔的压力、流速及旋转体转矩的变化规律。结果表明:随着偏心距的增大,旋转体转矩增大;斜射流口的出口平均流速在小偏心距变化微小,在大偏心距逐渐减小;随着水平夹角的增大,旋转体转矩减小;斜射流口的出口平均流速随着水平夹角的增大先增大后减小,且随着偏心距的增大其峰值点逐渐后移。 相似文献
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Pengju Hou Yongfeng Guo Dongxiang Shao Zongfeng Li Yeerbangli Wureli Lin Tang 《The International Journal of Advanced Manufacturing Technology》2014,73(1-4):229-239
Insulating zirconia has attracted increasing attention in industrial applications due to its excellent hardness, chemical stability, and corrosion resistance. However, insulating zirconia is difficult to machine by using traditional cutting techniques. In this paper, the high-speed wire electrical discharge machining (HS-WEDM) process of insulating zirconia is carried out with the assisting electrode method. The machining characteristics of insulating zirconia with HS-WEDM process are investigated, which include the study of effect of open-circuit voltage (U) on machining speed, discharge gap, surface roughness, surface microtopography, and electrical discharge status. The experimental results indicate that when U is changed from 90 to 150 V, the machining speed increases from 1.02 to 2.61 mm2/min and the machining gap increases from 15.55 to 26.67 μm. With the increasing U, the percentage of electrical discharge with high resistance increases, the percentage of electrical discharge with low resistance changes only slightly, and the percentage of short circuit with low resistance decreases. Moreover, when grooves are machined into transverse and longitudinal direction of the workpiece, the two machined surfaces of one grove present different surface characteristics. 相似文献
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混粉电火花加工中粉末对工件表面的影响 总被引:1,自引:1,他引:1
对不同加工条件下混粉电火花加工后工件表面的硅含量进行了对比测量。实验结果表明:当峰值电流小于4A时,混粉电火花加工后的工件表面硅含量随峰值电流的增大而急剧减小,而当峰值电流大于4A时,工件表面硅含量随峰值电流的增大而缓慢增加;混粉电火花加工后的工件表面硅含量随脉宽的增大而增加;在其他加工条件相同的情况下,对于相同的单次放电脉冲能量,混粉电火花加工获得的工件表面硅含量随峰值电流变化的关系呈近似二次曲线。引入熵的概念,对产生上述结论的原因进行了分析,并解释了混粉电火花加工可以改善工件表面质量的机理。 相似文献
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In micro electrical discharge machining (EDM), because the material removal per single pulse discharge mainly determines the minimum machinable size of a micro EDM, decreasing the material removal per single pulse discharge is important. In this study, in order to decrease the material removal per single pulse discharge, high electric resistance materials such as single-crystal silicon are used for electrodes. Analytical results show that when the electrode resistance increases, the peak value of the discharge current decreases, whereas the pulse duration increases. In addition, the discharge energy decreases when increasing the resistance. Silicon is used as a tool electrode, and the effect of resistivity of the silicon tool electrode on the diameter of discharge craters generated on the stainless steel workpiece is examined. Experimental results reveal that with increasing silicon electrode resistivity, the diameter of discharge craters decreases. Because the diameter of discharge craters can be decreased to 0.5 μm, improved finished surfaces of Rz 0.03 μm are obtained. 相似文献
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针对临界导电模式下功率因数校正的问题,以BOOST电路为研究对象,推导了临界导电模式下功率因数校正电路的输入电流表达式,并详细分析了临界导电模式功率因数校正BOOST开关变换器的稳态特性.给出了开关频率与输入电压及功率的关系.提出了采用专用PFC控制芯片来调整开关管的开通时间,改善其关断条件,提高整个电路的工作效率,以... 相似文献